Charge Laptop directly with DC?

I don't think I would charge my Laptop or Chromebook using anything other than the supplied power cable/transformer.
I very recently bought a lithium power bank primarily for use on the boat and that is a possible source for recharging the laptop when off grid.

The power bank itself can be recharged directly via mains supply or solar. Or (via a separate device) engine alternator. At the moment I just have the mains recharging option as I am not expecting to be off grid long enough to need solar. However a solar panel is easily possible addition if I find it would be useful.

The power bank switches itself off if there is no power demand so that saves wasted energy powering only the inverter.

It's early days but the power bank although perhaps not the cheapest option took no fitting at all and it can stay with me if I change the boat.
 
Momac said:
I don't think I would charge my Laptop or Chromebook using anything other than the supplied power cable/transformer.
I very recently bought a lithium power bank primarily for use on the boat and that is a possible source for recharging the laptop when off grid.

The power bank itself can be recharged directly via mains supply or solar. Or (via a separate device) engine alternator. At the moment I just have the mains recharging option as I am not expecting to be off grid long enough to need solar. However a solar panel is easily possible addition if I find it would be useful.

The power bank switches itself off if there is no power demand so that saves wasted energy powering only the inverter.

It's early days but the power bank although perhaps not the cheapest option took no fitting at all and it can stay with me if I change the boat.
Click to expand...
I am working on getting the boat self sustained, ie that I don't need shore power to keep me topped up at all. Laptop is one of the biggest energy consumers, and since I can't work without it, I really need to find a way to make it work.
 
My Mac's regular charger is 140W ... which is around 15A. Can someone recommend a suitable 12V charger?
Does it still make a sense to do DC-DC or maybe better to use an inverter?
 
ditching the inverter is smart if you’re off-grid. Look at hobby RC power supplies too, they often have clean adjustable DC outputs.
 
DangerousPirate said:
I am working on getting the boat self sustained, ie that I don't need shore power to keep me topped up at all. Laptop is one of the biggest energy consumers, and since I can't work without it, I really need to find a way to make it work.
Click to expand...
An inverter is 90% efficient, as is a typical DC-DC converter, so no power saving using either. The only difference is, if you leave the inverter on when it's not doing anything it will still use about 0.5A. So you could just fit a small inverter and turn it off when it's not charging the laptop.

Fit as much solar as you can and consider Lithium, as it charges much, much faster.
 
Laptop power supplies are designed to power 3 aspects of the unit :

1. To charge the battery
2. To power the PC itself while battery charges
3. To power the extras such as CD / USB drives / additions etc.

The actual PC doesn't take much power in fact ... usually 12W or so - which is then regulated via a Voltage converter on the board to match the 3.3 or 5V board etc.
The main bulk of adaptor power goes to charge the battery and power any extras plugged in .. this is why quite often cheap iniversal 12V car adaptors for PC's fail ... they cannot cover this. Best is to try and get the Brand specific 12v Adaptor .. if not then go for a decent universal ... a visit to local Computer Shop is recc'd.
Also note that the battery serves 4 purposes :
1.; To power the PC when travelling
2. To be a regulator of input power
3. To provide boost power when power hungry additions plugged in
4 To maintain the onboard battery cell to keep the BIOS

I can run all my IBM Thinkpads .... Lenovo later Pads ... Acer ... Asus .... HP etc (I have loads of them because my employees insist on upgrade machines ... so I take the old and re-purpose) ... on 12v direct from the boats system .. without adaptors. But as soon as I add a CD player ... extra item that requires power as well - the lack of that extra voltage level can limit.
When I connect to 12v direct - I isolate the battery in the PC ... to prevent it draining the power input ... simple tape on the contacts is enough.

Just commenting ... I have a 12v PoS unit ... a Point of Sale small desktop PC specially designed to run off 12v .. and I keep meaning to install on my 38 ... one day I will !!
 
A better route maybe is to get a new or even second hand ultra low powered boat pc/laptop. My Samsung laptop uses 35W max and you can get mini PCs now down to 20W. With sleep mode enabled and auto off on the screen the average Watts should be way less, such that there is no real problem anymore. A Pi less again. A DC/DC supply is easy and effective and helps further a bit. An extra benefit is it can mean you don’t need an inverter on all the time and that can save as much power again. The quiescent power draw of my Mastervolt inverter on standby is about 10W. Worse on some other brands.
 
DangerousPirate said:
I mean, I tried to find one but was not successful. Not for the required output.

Laptop's an Asus Tuf A15 . . .
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Do you have the version of the A15 which does USB-C charging? If so, this should work: https://www.amazon.co.uk/UGREEN-150W-3C1A-Car-Charger/dp/B0CPF4RDFQ?af=eyJxdWFydHpWZWhpY2xlIjoiMjktMTA1MTkifQ==&dib=eyJ2IjoiMSJ9.RRl6FAfGJ5EIsv9Nh7NKy5iUXD0F-SJ0ztDqzSgJ5bxJtIuG9sc6QuxOwNC8M9mH_8fIc54q9G0WYDZU9Bb_c5w30dqESolx1qHF00jOG86JIA_KCF-pFX9y-RELWsAvc75gATPp1ij7fZeL8RJ8N_Z4AInuljmwXT0BjqBCT51BYu52az0JJdRi_5eMhtXvWr7yTEPFD_aWG1DIQd9VA0qAAm06ZT7YwJRHskAif5c.8_QZy5cSLzvzR8ssb3mkVBTEQGmRMmqWQ_o_VIr4a5k&dib_tag=se&keywords=HKY+150W+Car+Charger&qid=1748001889&sr=8-4

If not, then this one is explicitly compatible with the TUF A15: https://www.amazon.com/HKY-G15-G513IH-G15-G512LI-A15-FA506-A18-150P1A/dp/B0CLR71PQY

Most models of the A15 are ok with 150 watts. If you have a special extra power gaming GUI, though, you might need more. ChatGPT is your friend here.

In the worst case, you can use your existing AC adapter with a small inverter. The difference in efficiency is not huge.
 
I have used a cheap cigarette usb C laptop charger with my beefy Dell CAD laptop. The power rating isn't as high as the mains charger and I get a warning saying that I have plugged into a low power charger. But... even in heavy use the adaptor is enough to keep the laptop running and fully charged. The average power usage is well under what the power supply is rated for and during high loads the laptop draws extra from the battery.
 
Dogone said:
A better route maybe is to get a new or even second hand ultra low powered boat pc/laptop. My Samsung laptop uses 35W max and you can get mini PCs now down to 20W. With sleep mode enabled and auto off on the screen the average Watts should be way less, such that there is no real problem anymore. A Pi less again. A DC/DC supply is easy and effective and helps further a bit. An extra benefit is it can mean you don’t need an inverter on all the time and that can save as much power again. The quiescent power draw of my Mastervolt inverter on standby is about 10W. Worse on some other brands.
Click to expand...
The OP is using a very high powered gaming computer, which I bet he wants for gaming. A low powered mini PC will not work for that use case.

But he should not be using a gaming computer for navigation. If he wants to run OpenCPN and other nav programs, then indeed a mini PC is a great solution, and is what I use myself. The latest ones use as little as single digits of watts, and can be powered by a USB-C PD car charger. You can buy 12v/24v powered USB-C PD chargers on Ebay, but only up to 65w or so, so not for the OP's gaming computer.
 
PaulRainbow said:
An inverter is 90% efficient, as is a typical DC-DC converter, so no power saving using either. The only difference is, if you leave the inverter on when it's not doing anything it will still use about 0.5A. So you could just fit a small inverter and turn it off when it's not charging the laptop.

Fit as much solar as you can and consider Lithium, as it charges much, much faster.
Click to expand...
Manufacturers usually quote efficiency at rated load because it looks good but if you are using a 1000w inverter at only 200w the efficiency may only be 70%. The same applies to DC-DC converters so it is probably best to have only one power conversion and size the supply to suit the load and not an excessive size just to be safe. Only actual measurements will give you the true picture.
I was caught out by this when the battery life on an underwater instrument turned out to be much less than expected because the DC-DC converter was sized for peak load and was very inefficient at 5% load.
 
andsarkit said:
Manufacturers usually quote efficiency at rated load because it looks good but if you are using a 1000w inverter at only 200w the efficiency may only be 70%. The same applies to DC-DC converters so it is probably best to have only one power conversion and size the supply to suit the load and not an excessive size just to be safe. Only actual measurements will give you the true picture.
I was caught out by this when the battery life on an underwater instrument turned out to be much less than expected because the DC-DC converter was sized for peak load and was very inefficient at 5% load.
Click to expand...
A Victron Phoenix 300w will be operating at more than 90% when running a 200w load.

That's not going to be materially different from the efficiency of a DC-DC converter.

HOWEVER, to make a fair comparison, you also have to count the efficiency of the AC charger, which takes another chunk of power to convert the AC power to the DC power needed for the laptop.

Still, I don't think +/- 10 or 15 watts is a big deal when you're running a 200w load.

I would go with the car charger in the OP's place, but using a small inverter would not be the end of the world at all.
 
pawelg said:
My Mac's regular charger is 140W ... which is around 15A. Can someone recommend a suitable 12V charger?
Does it still make a sense to do DC-DC or maybe better to use an inverter?
Click to expand...
Use a Belkin USB-C car charger - Belkin has a Connected Equipment Warranty and they make chargers which supply, I think, 20W or 30W.

EDIT: Amazon.co.uk

There is zero chance your MacBook needs 140W - that will give you faster charging, but my MacBook charges from a 12v Belkin USB-C charger in 2 or 3 hours, even when in use.

A big part of Apple's engineering goal now is to use fewer watts to get the same performance, so that they can get the same battery life using smaller batteries and make their laptops slipper. This is why they moved to ARM chips, although the same was true of their later Intel models. I guess a MacBook is typically using 15W or less, because it will always continue to charge off lower-wattage USB-C supplies. It only uses more if you hammer the CPU with Photoshop or something.
 
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